Azomethine dyes, in particular azomethine dyes with a p-dialkylaminophenyl group bonded to the nitrogen atom of an imine, are formed by means of an oxidizing coupling reaction between active methylenes or phenols and N,N-dialkyl-p-phenylenediamines. These dyes, due to the variety of their yellow, red, magenta, blue and cyan color tones, have come to be widely used as image-forming dyes in silver halide color photographic materials employing a color subtractive process using a mixture of the three colors yellow, magenta and cyan. Blue and cyan dyes are formed from phenols, naphthols or 2,4-diphenylimidazoles and the like, magenta and blue dyes are formed from 5-pyrazolones, acylacetonitriles, 1H-pyrazolo[1,5-a]-benzimidazoles, 1H-pyrazolo[5,1-c]-1,2,4-triazoles, 1H-pyrazolo[ 2,3-b]-1,2,4-triazoles and the like, and yellow dyes are formed from acylacetanilides, diacylmethanes, malondianilides and the like. Dyes of this kind are disclosed in, for example, JP-A-60-186567, JP-A-63-145281, and JP-A-63-113077 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Recent years have seen the introduction of new color image-forming methods such as color electrophotography, ink-jet systems, and thermo-sensitive transfer systems, and at the same time demand is increasing for filters for liquid crystal color televisions and solid-state image pick-up tubes in tandem with developments in electronic imaging, so that azomethine dyes are being studied and applied not only in color photographs but in a variety of systems and products.
Conventional azomethine dyes often suffer from defects in that they require a large number of production processes, are costly, and lack stability. Accordingly there has been a strong demand for improvement.